Consulting services are provided to NIH researchers on problems requiring knowledge of advanced techniques in applied mathematics, physics, and statistics. Projects have been completed relating to interpolation errors in computerized tomography, to the occurrence of audiologic defects in patients and relatives of patients having osteogenesis imperfecta, on the consequences of head injuries for life span, and on the occurrence and time course of posttraumatic epilepsy. A project has been started on the estimation of errors in parameters measured by positron emission tomography, and a theory has been developed to estimate expected error from the data. Another project with the Clinical Center is on the use of ultrasonic measurements to characterize tongue position in speech. The biochemical characterization of coated and uncoated vesicles by a combination of ultracentrifugal techniques and light scattering is another project recently initiated.